Single-ended electric incandescent lamp filament support



Sept. 24, 1968 J. 5. CARDWELL; JR 3,403,280

SINGLE-ENDED ELECTRIC INCANDESCENT LAMP FILAMENT SUPPORT Filed March 4, 1966 lnvehi'ori John G; Cai-dweLL, JT.

United States Patent 3,403,280 SINGLE-ENDED ELECTRIC INCANDESCENT LAMP FILAMENT SUPPORT John G. Cardwell, Jr., Kirtland, Ohio, assignor to General Electric Company, a corporation of New York Filed Mar. 4, 1966, Ser. No. 531,799 6 Claims. (Cl. 313-271) This invention relates to electric incandescent lamps and more particularly to the filament supporting or mount structure for such lamps.

Even more particularly, this invention pertains to single-ended electric incandescent lamps having a generally tubular bulb which is closed at one end by a pinch seal. These single-ended incandescent lamps usually comprise a bulb or envelope, a filament, support means for the filament, and a pinch seal through which extend lead-in conductors. The main functions of the support means are to align the filament along the longitudinal axis of the bulb and to maintain this alignment when the lamp is subjected to the shock and vibration incurred in shipment and use. The strength required of the support means is greatly dependent on the filament weight.

In certain prior art constructions, the filament support means are free to move or sway within the lamp under the influence of external shock and vibration; the results can be disastrous especially when heavy filaments, such as coiled-coils, are involved. To strengthen the support with relation to the filament, it has been common practice to provide bridge members and other such auxiliary Components with their added complications of assembly and cost.

Therefore, it is the object of my invention to provide an improved support member which will adequately support a relatively heavy filament coil structure prior to and during assembly with the bulb, will align the coil in all directions, eliminate the need for a bridge, and will serve as a mount brace as well as a current conductor.

Briefly stated, in accordance with one aspect of the invention, a single-ended incandescent lamp, having a generally tubular bulb and a pinch seal at its end, is provided with a generally U-shaped support member comprising an intermediate bend portion to which one end of the filament is connected, and side leg portions which extend longitudinally of the axis of the bulb and bear against the inside of the bulb. One side leg portion extends into and is connected within the pinch seal to a lead-in conductor; the other side leg portion extends into and terminates within the pinch seal.

Further features and advantages of the invention will appear from the following detailed description to be read in conjunction with the following drawings wherein like reference symbols denote corresponding parts throughout the several views.

FIG. 1 is a side elevation of a single-ended halogen incandescent lamp embodying the invention.

FIG. 2 is an enlarged view of the intermediate bend portion of the U-shaped support member illustrating a preferred form of connection to one end of the filament.

FIG. 3 is a transverse section view of the lamp along section lines 33 of FIG. 1.

FIG. 4 illustrates the assembled metal components or mount structure of the lamp prior to their insertion within the bulb.

Referring to FIG. 1 of the drawing, the single-ended incandescent lamp comprises a generally tubular envelope or bulb 11, of vitreous material such as quartz or a high silica material, having a dome-shaped end 12 opposite the pinch seal 13 and, in this case, an enlarged bulbous portion 14. A pair of lead-in conductors comprise outer lead portions 15 and 16, preferably of molybdenum, connected to foil portions 17 and 18, which are 3,403,280 Patented Sept. 24, 1968 also preferably of molybdenum and are hermetically sealed in the pinch seal 13.

The envelope 11 preferably contains an inert gas filling and may also contain a reactive atmosphere such as a halogen to produce a regenerative cycle whereby the evaporated tungsten from the filament reacts with the halogen and is redeposited on the filament. A regenerative cycle employing iodine is more fully discussed and dis.- closed in Patent 2,883,571-Fridrich et al.

The U-shaped support 19 comprises an intermediate bend portion 20 and side leg portions 21 and 22. In accordance with the invention, side leg portions 21 and 22 bear against the inner wall of the bulb 11. The leg portions bearing against the Wall of the bulb virtually secure it against displacement in all directions. Intermediate bend portion 20, in this embodiment has a helically coiled section 23, which has its longitudinal axis aligned with the longitudinal axis of the bulb 11. The bend portion 20 engages the walls of the bulb 11 and at least one side thereof conforms to and engages a dome-shaped end 12 of bulb. This engagement serves to align coil section 23 of the intermediate bend portion 20 axially of the bulb 11.

Side leg 21 is attached to foil portion 17 of the lead-in conductor 15 within pinch seal 13, preferably by welding and with a tab of platinum-clad molybdenum foil interposed therebetween. Side leg 22 extends into and terminates within the pinch seal 13.

A spud or leg member 24, which is preferably made of tungsten wire, has a helical end section 25 (FIG. 2) which is fitted as a mandrel into the primary coiling of a secondary turn of the coiled-coil filament 27 adjacent to the intermediate 'bend portion 20, and a straight section 26 which extends along the axis of the filament into engagement with the coiled section 23 of the intermediate portion 20 where it is preferably tack-welded. Since straight section 26 extends along the axis of the filament as a leg member, a precise alignment of the filament in the bulb is obtained.

The other end of the filament has a longitudinal single coiled leg 28 containing one end of a spud wire 29 to which it is preferably welded. The other end of spud 29 is welded to foil 18 with a platinum-clad molybdenum foil tab interposed therebetween.

When desired to minimize heating of the pinch seal, there is provided a reflector disc 30 of tungsten which has a hole 31 for the passage of filament leg 28, and arcuate sections 32 (FIG. 3) removed adjacent to the legs 21 and 22 of the U-shaped frame to avoid short-circuiting the filament. The disc 30 is frictionally engaged with the filament leg 28, but, to avoid turning of the disc, disc support 33 is used. Disc support 33 is a tungsten wire having a helical end 34 (FIG. 4) to embrace by a screwon action, the exterior of the leg 28, and hook end 35 which loops over the periphery of the disc. The need for the heat deflecting disc, in some cases, will be appreciated when it is realized that in the type of lamp here involved the filament 27 may be designed to dissipate 1000 watts in a bulb 11 formed from tubing of about inch di ameter, and the temperature of the pinch seal 13 must not exced about 350 C. in order to avoid destructive oxidation of the molybdenum lead-in conductors 15, 16 and especially the foils 17, 18.

In one method of assembly (see FIG. 4), U-shaped support 19 has its side leg portions 21 and 22 spread apart so that the distance between them is greater than the diameter of the bulb 11 in which they will be placed. This effect can be produce-d by either bending one or both of the side legs outward (from each other. Filament 27 is brought into place between the two side legs and is attached to the helical coil 23 of the intermediate bend portion 20 of the support by means of spud 24. The helical section 25 of spud 24 is engaged in the filament 27; its

straight section is then threaded up through the opening in helical coil 23 where it is preferably tack-welded to secure it. The free end of the filament leg 28 is then threaded to the helical end 34 of the disc support 33 while also being threaded through the hole 31 in disc 30 both of which are frictionally engaged with the filament. When the support 33 has been put in the proper position the hook end 35 is looped over the periphery of the disc 30 at one of its arcuate sections 32. Spud wire 29 is then inserted into the filament leg 28, preferably for its full length, where it is spot-welded to secure it. The foil portions 17 and 18 of the lead-in conductors are then spot-welded by means of an inter-spaced tab of platinum-clad molybdenum foil to the respective side leg 21 and spud wire 29. When this mount assembly is completed, it is fed into the bulb 11 until the intermediate bend portion 20 frictionally engages dome-shaped portion 12 of the bulb. In accordance with the invention, the side legs 21, 22 bear firmly against the inner wall of bulb 11. This aids in holding the weight of the filament during the pinch sealing. Also the upper end of the filament is aligned along the longitudinal axis of the bulb since helical coil 23 is positioned so that when the U-shaped support 19 engages the bulb it will be axially aligned. The lead-in conductors 15 and 16 are held by exterior means while the pinch seal 13 is performed. Side leg 21 extends into and terminates within the pinch seal. In addition, the foil portions 17 and 18 are hermetically sealed within the pinch 13 with lead-ins 15, 16 extending out of the pinch seal.

The bulb 11 is finally exhausted of air and filled with inert gas and halogen through an exhaust tube which is then sealed or tipped off as shown at 36.

It will be evident that the side leg portions 21, 22 of the U-shaped support 19 bearing against the wall of the tubular bulb 11 give added support to the filament by retaining its alignment when the lamp is subjected to forces from all directions. Since the U-shaped support 19 is not free to move within the bulb, the filament 27 is held securely at both ends. Also, the U-shaped support, as noted in the method of assembly, helps support the Weight of the filament during the pinch sealing of the bulb. In the specific embodiment shown, the helical coil 23, the spud 24, the dome-shaped end 12 of the bulb, and the generally dome-shaped intermediate portion 20 of the U-shaped support, all in combination, insure proper alignment and firm support of the filament within the bulb.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A single-ended electric incandescent lamp comprising a generally tubular bulb of vitreous material having a pinch seal at one end,

a pair of lead-in conductors extending through said pinch seal,

a coiled filament extending longitudinally of said bulb and having a leg portion at one end connected to one of said lead-in conductors,

and a generally U-shaped support member comprising an intermediate bend portion to which the other end of said filament is connected,

and side leg portions of said support member extending longitudinally downward from said intermediate portion and bearing against the inner wall of the bulb, one of said side leg portions extending into said pinch seal and connected to the other lead-in conductor, the other side leg portion extending into and terminating within said pinch seal.

2. A single-ended incandescent lamp as set forth in claim 1 wherein the intermediate bend portion of the U shaped support member at its mid-section is a helical coil in the bulb axis, and a leg member extends from the proximate end of the filament into said coil and is secured thereto.

3. A single-ended incandescent lamp as set forth in claim 2 wherein the said leg member is a wire spud which comprises a helical end section which is fitted as a mandrel in the primary coiling of a secondary turn of the filament, and a straight section which is aligned along the longitudinal axis of the filament and extends into the coil of said intermediae bend portion.

4. A single-ended incandescent lamp as set forth in claim 1 'Wherein the bulb end opposite from the pinch seal is generally dome-shaped, and at least a part of the bend portion of said support member is correspondingly curved and in frictional engagement with the said dome-shaped bulb end.

5. A single-ended lamp as set forth in claim 1 including a reflector disc disposed transversely of the bulb axis between the pinch seal and the proximate end of the filament, and means seeming said disc to the leg portion at the said proximate end of the filament in insulating relation with respect to the side leg portions of the U-shaped support member.

6. A single-ended incandescent lamp as set forth in claim 1 wherein a reflector disc is attached to the leg portion at the end of the filament which is connected to said one lead-in conductor by virtue of a hole through which said end of the filament extends, said disc having arcuate portions removed from it adjacent to the side leg portions of the U-shaped support member, said disc being held by a support wire which has a helical section in screw-thread engagement with said end of the filament and a hook which engages the periphery of said disc.

References Cited UNITED STATES PATENTS 3,253,178 5/1966 Fantur 313-271 3,270,238 8/1966 Mosby 313-279 3,283,198 11/1966 Bellott et al 3l3240 3,343,021 9/1967 Burnett et a1. 313-42 JOHN W. HUCKERT, Primary Examiner. J. R. SHEWMAKER, Assistant Examiner. 

1. A SINGLE-ENDED ELECTRIC INCANDESCENT LAMP COMPRISING A GENERALLY TUBULAR BULB OF VITREOUS MATERIAL HAVING A PINCH SEAL AT ONE END, A PAIR OF LEAD-IN CONDUCTORS EXTENDING THROUGH SAID PINCH SEAL, A COILED FILAMENT EXTENDING LONGITUDINALLY OF SAID BULB AND HAVING A LEG PORTION AT ONE END CONNECTED TO ONE OF SAID LEAD-IN CONDUCTORS, AND A GENERALLY U-SHAPED SUPPORT MEMBER COMPRISING AN INTERMEDIATE BEND PORTION TO WHICH THE OTHER END OF SAID FILAMENT IS CONNECTED, AND SIDE LEG PORTIONS OF SAID SUPPORT MEMBER EXTENDING LONGITUDINALLY DOWNWARDLY FROM SAID INTERMEDIATE PORTION AND BEARING AGAINST THE INNER WALL OF THE BULB, ONE OF SAID SIDE LEG PORTIONS EXTENDING INTO SAID PINCH SEAL AND CONNECTED TO THE OTHER LEAD-IN CONDUCTOR, THE OTHER SIDE LEG PORTION EXTENDING INTO AND TERMINATING WITHIN SAID PINCH SEAL. 